10.1021/jp5080048.s001 Hui-Yan Zhao Hui-Yan Zhao Jing Wang Jing Wang Xiu-Jie Su Xiu-Jie Su Dong-Bo Zhang Dong-Bo Zhang Ying Liu Ying Liu Ice Carbons American Chemical Society 2014 oxygen nets carbon phases ice CarbonsOn bulk modulus superhard materials tP 12 superdense carbon allotropes hardness 94.1 GPa 1.4 GPa carbon structures ice phases sp 3 2014-11-26 00:00:00 Journal contribution https://acs.figshare.com/articles/journal_contribution/Ice_Carbons/2231539 On the basis of the topologically distinct oxygen nets of crystalline ice phases, a series of carbon structures with sp<sup>3</sup> bonding are constructed. Five new low-energy polymorphous phases of carbon, named “ice carbons”, are predicted by using the first-principles calculations. Their hardnesses are about 88.5–98.5% that of diamond, indicating that these new carbon phases are superhard materials. In particular, the new “<i>ice</i><sup>III</sup>-carbon” has the highest hardness 94.1 GPa that only 1.4 GPa smaller than that of diamond. Moreover, it also has slightly lower bulk modulus, which display similar properties with <i>h</i>P3, <i>t</i>I12, and <i>t</i>P12 superdense carbon allotropes.